Triclocarban has been used successfully as an antimicrobial active ingredient in antimicrobial bar soaps (solid soap) for almost 40 years. Triclocarban is only available in powdered form, e.g. crystalline (unground) or finely micronized. In contrast to other common antimicrobial active ingredients such as triclosan, chlorhexidine or chloroxylenol, which can be used both in antimicrobial bar soaps and in liquid soaps, triclocarban has hitherto not been incorporated into liquid soap.
The reason for this is the extremely low, inadequate solubility of triclocarban in liquid soaps and their main components. For example, the solubility of triclocarban in water, the main component of liquid soaps, is, at about 50-100 ppb, virtually zero. The solubility of triclocarban in common surfactants such as sodium laureth sulphate or cocamidopropylbetain and in common solvents such as glycerol or propylene glycol is well below 1%.
It is therefore problematic to incorporate triclocarban, given its activity profile and use concentrations known from bar soaps, into liquid soaps too.
Liquid soaps are here taken to mean washing products intended for hands and body, i.e. liquid soaps for hand and body, shower and/or bath gels, combined liquid shower and care products, such as shower gel having a body lotion function and the like.
The concentration of triclocarban in liquid soaps should preferably be from 0.3 to 0.5% for such products, although somewhat lower (0.1 to 0.25%) or somewhat higher (0.55 to 0.7%) concentrations can also be tried depending on the composition of the soap and microbiological testing.
Attempts have therefore been made to dissolve triclocarban in concentrations of 0.1 or 0.7% in commercially available liquid soaps as in Table 1 and to test for crystallization or undesired changes in appearance or chemical active ingredient instability over a few weeks at refrigeration temperature, room temperature and 40.degree. C. (Preventol SB was used, min. 97% triclocarban).
TABLE 1 ______________________________________ List of liquid soaps/shower and bath gels available on the German/European market Shower and bath gel Manufacturer Supplier ______________________________________ CD .RTM. Elida Gibbs Rexona .RTM. Elida Gibbs Satina .RTM. Bayer AG Azzurra paglieri .RTM. Scholl Fa (marine) .RTM. Henkel Lux (Wash & Lotion) Lever Nivea (shower) .RTM. Beiersdorf Ellen Betrix (Sport + Beauty) .RTM. Betrix Cliff (ocean fresh) .RTM. Procter & Gamble dusch das .RTM. Linger + Fishcer ______________________________________ Liquid hand soap Manufacturer ______________________________________ Seba MEBINACOR .RTM.d .RTM. Sebapharma Satina .RTM. Bayer AG Lux .RTM. Lever Kd .RTM. Tag-Vertriebs GmbH Dove (cream wash) .RTM. Lever Kur (cream soap) .RTM. win cosmetic/Aldi ______________________________________ List of liquid soaps available on the US market Liquid soaps Producer ______________________________________ Jergens liquid soap .RTM. The Andrew Jergens Company Lever 2000 liquid soap .RTM. Lever Brothers Company Clean & Smooth .RTM. Benckiser Consumer Products Inc. ______________________________________
Triclocarban as powder cannot be dissolved in any of the 22 liquid soaps tested, not even with warming to about 50.degree. C.
In a second test series, a 10% strength triclocarbon presolution (triclocarban dissolved in a solubilizer/emulsifier of the PO/EO copolymer type) is incorporated into the above liquid soaps such that triclocarban is present in concentrations of 0.7%. Virtually all of the triclocarban crystallized out after just a few hours up to a maximum of 24 hours in 20 products. In the remaining 2 products, triclocarban also crystallized out, within a period of weeks. However, liquid soaps must have shelf lives of many months, meaning that these formulations too are unsuitable for triclocarban.
In contrast, triclosan can be incorporated into said liquid soaps in an amount of 0.7%.
The object of the invention was therefore to develop special, cosmetically exacting, ecologically and economically viable and microbiologically effective liquid soaps based on triclocarban which at the same time have a long shelf life.
Surprisingly, it has now been found that despite a high content of water and surfactants, cosmetically high-value and stable liquid soaps can be prepared.